JP2001148538A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a red-light semiconductor laser device which oscillates a high power fundamental mode. SOLUTION: A semiconductor laser 24, having a Ga1-z1Alz1N/GaN superlattice clad layer 12, a GaN optical guide layer 13, an In1-z2Gaz2N/In1-z3Gaz3N multilayer quantum well active layer 14, a Ga1-z4Alz4N carrier blocking layer, a GaN optical guide layer 16, a Ga1-z1Alz1N/GaN superlattice clad layer 17, a GaN contact layer 18, etc., formed on a GaN substrate 11 excites a surface- emitting type semiconductor element having an In0.5(Ga1-x5Alx5)0.5P clad layer 32, an In0.5(Ga1-x2Alx2)0.5P lower light-confining layer 33, an In0.5(Ga1-x3Alx30.5P/ In0.5(Ga1-x4Alx4)0.5P multilayer quantum well active layer 34, an In0.5(Ga1-x2Alx2)0.5 P lower light-confining layer 35, an In0.5Al0.5P/In0.5(Ga1-x1Alx1)0.5P distributed reflection film 36, an SiO2/ZrO2 distributed reflection film 37, etc., formed on a GaAs substrate 31, to thereby obtaining laser oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser device, and more particularly to a surface-emitting type semiconductor laser device using a semiconductor laser element as an excitation light source.

[0002]

2. Description of the Related Art As the functions and performance of optical information / image processing apparatuses, printing apparatuses, and the like have increased, the semiconductor laser devices used in these apparatuses have been required to have higher output and higher quality laser beams. ing.

As a short-wavelength semiconductor laser device in the 410 nm band, Jpn. Appl. Phys. Lett., Vol. 37.pp.
In 020, after GaN is formed on a sapphire substrate, Ga is formed by selective growth using SiO ₂ as a mask.
After forming N, the n-GaN buffer layer, the n-InGaN crack prevention layer, the AlGaN / n-GaN modulation-doped superlattice cladding layer, the n-GaN optical waveguide layer, the undoped InGaN /
n-InGaN multiple quantum well active layer, p-AlGaN carrier block layer, p-GaN optical waveguide layer, AlGaN /
A structure comprising a p-GaN modulation-doped superlattice cladding layer and a p-GaN contact layer has been reported. However, in this semiconductor laser device, since the stripe width is as narrow as 2 μm, an optical output of only about 100 mW is obtained.

On the other hand, in the conventional red single semiconductor laser device, in order to increase the output and oscillate the fundamental mode,
Attempts have been made to adopt a window structure, but currently about 50 mW is the practical limit.

[0005] In recent years, in red semiconductor laser devices,
IEEE PHOTONICS TECHNOLOGY LETTER, VOL.
11 P791 describes that a single-mode semiconductor laser with a wavelength of 660 nm and an output of 400 mW was realized. However, this structure has a problem that side lobes are generated in the transverse mode and beam characteristics are poor. In addition, despite the broad area structure, there is also a problem that it is difficult to further increase the output and the reliability over time is low because of the high end face light density.

As another method of increasing the output, there is a semiconductor laser-excited SHG solid-state laser. However, since the fluorescence lifetime of a rare earth element in a laser crystal is very long,
It has been difficult to obtain a high-speed modulated beam of an oscillation beam by direct modulation of a semiconductor laser for excitation. Also, SHG
There is also a problem that efficiency is low because light is used.

Further, in order to oscillate a high output and fundamental transverse mode, US Pat. No. 5,628,783 discloses a surface emitting laser device excited by a semiconductor laser. But,
There is only a description of shortening the wavelength by using SHG, but no description is given of a high-efficiency short-wavelength surface emitting laser that does not use SHG.

[0008]

In a semiconductor laser device having a red wavelength region as described above, it has been extremely difficult to obtain high output and fundamental mode oscillation until now.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a semiconductor laser device having high efficiency, high output, and high reliability in fundamental mode oscillation.

[0010]

According to the present invention, there is provided a semiconductor laser device comprising: an excitation light source comprising a semiconductor laser element using InGaN or GaN for an active layer; and a substrate, which is excited by the excitation light source and emits laser light. And a surface-emitting type semiconductor device provided with an active layer made of InGaAlP or InGaP.

Another semiconductor laser device of the present invention is an InG
an excitation light source composed of a semiconductor laser element using aN or GaN for an active layer; and InGaAlP or InGa on a substrate, which is excited by the excitation light source and emits laser light.
The semiconductor device comprises a semiconductor layer formed by stacking active layers made of P, and a surface-emitting type semiconductor device having mirrors at both end surfaces in the stacking direction of the semiconductor layer.

Another semiconductor laser device according to the present invention is a semiconductor laser device comprising:
An excitation light source comprising a semiconductor laser element using As or InGaNAs for an active layer, and InGaAlP or InGaAlP or InGaN on a substrate which is excited by the excitation light source and emits laser light.
And a surface-emitting type semiconductor device provided with an active layer made of GaP.

[0013] Another semiconductor laser device of the present invention is a semiconductor laser device comprising GaN
An excitation light source composed of a semiconductor laser element using As or InGaNAs as an active layer, and a semiconductor layer formed by laminating an active layer composed of InGaAlP or InGaP on a substrate, which emits laser light when excited by the excitation light source; And a surface-emitting type semiconductor device having mirrors on both end surfaces in the stacking direction of the semiconductor layers.

Another semiconductor laser device of the present invention is an InG
an excitation light source comprising a semiconductor laser element using aN or GaN for an active layer; a surface emitting semiconductor element provided with an active layer of InGaAlP or InGaP on a substrate, which is excited by the excitation light source; A mirror formed on the substrate side or the opposite side of the active layer of the surface-emitting type semiconductor element, and an external mirror forming a resonator; It is characterized by outputting laser light.

[0015] Another semiconductor laser device of the present invention is a semiconductor laser device comprising:
An excitation light source comprising a semiconductor laser element using As or InGaNAs for an active layer; a surface-emitting type semiconductor element having an active layer made of InGaAlP or InGaP on a substrate which is excited by the excitation light source; An external mirror constituting a resonator and a mirror formed on the substrate side of the active layer of the surface-emitting type semiconductor element or on the side opposite to the substrate, which is disposed outside the semiconductor element,
The laser light is output from the external mirror.

The semiconductor laser device has a stripe-shaped current injection window, and the width of the stripe serving as the current injection window is preferably 5 μm or more.

Further, it is desirable that the wavelength of the laser beam is not less than 600 nm and not more than 700 nm.

[0018]

According to the semiconductor laser device of the present invention, the semiconductor laser element whose active layer is made of InGaN or GaN is used as an excitation light source, and the active layer is made of InGaAlP or InGa.
Since laser oscillation is obtained by a surface emitting semiconductor element made of GaP, a broad area semiconductor laser element can be used as a semiconductor laser element for excitation, and a high output of, for example, 1 W to 10 W can be achieved. . Accordingly, a red laser device having an oscillation output of several hundred mW to several W can be obtained.

Further, since a semiconductor laser element is used as an excitation light source, it is possible to obtain high-output and side mode-free fundamental transverse mode oscillation.

In the active layer of the semiconductor laser device, Ga
Even when NAs or InGaNAs are used, red, side mode-free fundamental transverse mode oscillation can be obtained as described above.

Further, by using an external mirror, even if a side lobe is generated, a slit or the like can be suppressed by inserting it into the resonator. In addition, a semiconductor laser element can be used as an excitation light source. Therefore, it is possible to obtain a laser device capable of performing CW operation with high efficiency at low cost.

Further, high-speed modulated light can be obtained by directly modulating the semiconductor laser element which is an excitation light source.

Further, the semiconductor laser device of the present invention does not diffuse Mg or the like as a doping material unlike a normal current injection semiconductor laser device because it is photo-excited. The life of the laser device can be extended.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a 360 nm band semiconductor laser device for constituting a semiconductor laser device according to a first embodiment of the present invention. FIG. 2 shows an oscillating surface emitting semiconductor device.

First, the semiconductor laser device will be described with reference to FIG. Jpn.Appl.phys.Lett., Vo, 1998
After GaN was formed on the sapphire substrate by the method described in l.37.pp.L1020, GaN was formed using selective growth using SiO ₂ as a mask, and then the sapphire substrate was peeled off. Forming a GaN (0001) substrate 11; The n-GaN (00
01) n-Ga1 _{-z1 Alz1} N / GaN superlattice cladding layer 12 (0 <z1 <1), n or i-GaN optical waveguide layer 13, _{In1 -z2 Gaz2} N (Si-doped) ) / In _1-Z3 G
a _Z3 N multiple quantum well active layer 14 (0 <z2 <z3 <0.5), p−
Ga _1-z4 Al _z4 N carrier blocking layer (0 <z4 <0.
5) 15, n or i-GaN optical waveguide layer 16, p-Ga
_1-z1 Al _z1 N / GaN superlattice cladding layer 17 (0 <z1 <
1), a p-GaN contact layer 18 is formed. An insulating film 19 is formed thereon, and 100
The insulating film 19 in a stripe region of about μm is removed, and a p-side electrode 20 is formed thereon. Next, the substrate 11 is polished, an n-side electrode 21 is formed, and a resonator is formed by cleavage. After that, a high-reflection coat and a low-reflection coat are applied, and the semiconductor laser device 24 is completed by chipping.

Next, a surface emitting semiconductor device will be described with reference to FIG. Here, λ described later is a wavelength oscillated by light excitation, and n _InAlP , n _InGaAlP , n _SiO2 , n
_ZrO2 is InAlP, InGaAlP, Si
This is the refractive index at the oscillation wavelength of O ₂ and ZrO ₂ .

GaAs substrate by metal organic chemical vapor deposition
In _0.5 (Ga _1-x5 Al _x5 ) _0.5 P clad layer 3
2, In _0.5 (Ga _1-x2 Al _x2 ) _0.5 P lower light confinement 3
3, In _0.5 (Ga _1-x3 Al _x3 ) _0.5 P / In _0.5 (Ga
_1-x4 Al _x4 ) _0.5 P multiple quantum well active layer 34, In _0.5 (G
a _1-x2 Al _x2 ) _0.5 P lower light confinement 35, 2 pairs of In
_0.5 Al _0.5 P (thickness is λ / 4n _InAlP ) / In _0.5 (Ga
_1-x1 Al _x1 ) _0.5 P (thickness λ / 4n _InGaAlP ) distributed reflection film 36 (this layer may be _omitted ). The above composition is 0
≦ x4 <x3 ≦ 1, x4 <x2 <x5 ≦ 1, 0 ≦ x3 <x1 ≦ x2 and x3
Those satisfying <x5 <1 are desirable. Thereafter, 12 pairs of SiO ₂ (having a thickness of λ / 4n) were formed by electron beam evaporation or the like.
_{SiO 2} ) / ZrO ₂ (thickness λ / 4n _{ZrO 2} ) distributed reflection film 37
Are laminated. Thereafter, the substrate is polished, and the GaAs substrate 31 in the light emitting region is removed with a sulfuric acid-based etchant. At this time, the etching is automatically performed with In _0.5 (Ga _1-x5 Al _x5 ) _0.5 P
The cladding layer 32 is exposed and the etching stops. Thereafter, a non-reflective coat 38 of ZrO ₂ (thickness λ / 4n _ZrO2 )
Is performed to form a chip by cleavage.
To complete.

The wavelength band emitted by the surface-emitting type semiconductor device can be controlled in the range from 600 nm to 700 nm from the In _0.5 (Ga _1-x4 Al _x4 ) _0.5 P quantum well active layer.

Next, a description will be given of a semiconductor laser device, and FIG.

In the present semiconductor laser device, a semiconductor laser element 24 serving as an excitation light source and a heat sink 43 are provided with 12 pairs of Si.
O ₂ (thickness λ / 4n _SiO2 ) / ZrO ₂ (thickness λ / 4n
_{ZrO 2} ) A surface-emitting type semiconductor device 39 having an end face on the side of the distributed reflection film 37 bonded thereto, a concave mirror 46 serving as an output mirror, and a concave surface of the concave mirror 46 and a distributed reflection film 37 of the surface-emitting type semiconductor device. A resonator 49 and a Brewster plate 45 in the external resonator 49 are provided. A wavelength selection element, for example, a lio filter or an etalon, or a plurality thereof may be inserted into the external resonator 49 whose polarization is controlled by the Brewster plate 45.

Excitation light emitted from the semiconductor laser device 24
47 is condensed inside the semiconductor layer of the surface-emitting type semiconductor element 39 by the lens 42, light emitted from the surface-emitting type semiconductor element 39 resonates by the external resonator 49, and oscillates red laser light 48 from the output mirror 46. I do.

GaAs substrate 31 of surface-emitting type semiconductor device 39
Is not transparent to the excitation light 47 of the semiconductor laser element 24 for excitation, so that the surface-emitting type semiconductor element 39 is excited from the side as shown in FIG.

Further, by directly modulating the semiconductor laser element 24, a modulated signal modulated at a high speed can be obtained. This is a characteristic that cannot be realized by the conventional solid-state laser.

Further, since the surface-emitting type semiconductor laser of this embodiment is optically pumped, heat generation due to current injection can be reduced and a long life can be realized, unlike a semiconductor laser device of ordinary current injection.

Further, since the lateral mode can be controlled by the external mirror, there is no side lobe. Should a side lobe occur, a slit or the like can be inserted into the resonator to suppress it.

In the present embodiment, since the GaAs substrate 31 is an absorption medium for oscillating light, a pinhole-shaped hole formed by thinning the GaAs substrate with high precision by etching or the like is used for mode control. Is also effective.

Next, a semiconductor laser device according to a second embodiment of the present invention will be described.

First, a surface-emitting type semiconductor element constituting the semiconductor laser device will be described, and a cross-sectional view thereof is shown in FIG. Here, λ described below is a wavelength oscillated by optical excitation, and n _InAlP , n _InGaAlP , and n _ZrO2 are _InAlP , respectively.
This is the refractive index at the oscillation wavelength of P, InGaAlP, and ZrO ₂ .

As shown in FIG. 4, 30 pairs of In _0.5 (Ga 2) are formed on a GaAs substrate 61 by metal organic chemical vapor deposition.
_1-x1 Al _x1 ) _0.5 P (thickness is λ / 4n _InGaAlP ) / In
_0.5 Al _0.5 P (thickness is λ / 4n _InAlP ) distributed reflection film 62,
In _0.5 (Ga _1-x2 Al _x2 ) _0.5 P Lower cladding layer 63, I
n _0.5 (Ga _1-x2 Al _x2 ) _0.5 P Lower optical confinement 64, In
_0.5 (Ga _1-x3 Al _x3 ) _0.5 P / In _0.5 (Ga _1-x4 Al _x4 )
_0.5 P multiple quantum well active layer 65, In _0.5 (Ga _1-x2 A
l _x2 ) _0.5 P upper optical confinement 66, In _0.5 (Ga _1-x5 Al
_x5 ) _0.5 P clad layers 67 are sequentially laminated. The above composition is 0
≦ x4 <x3 ≦ 1, x4 <x2 <x5 ≦ 1, 0 ≦ x3 <x1 ≦ x2 and x3
It is desirable to satisfy <x5 <1. ZrO ₂ (thickness is λ / 4n _ZrO2 ) anti-reflection coating 68 by electron beam evaporation
Are laminated. Thereafter, the substrate 61 is polished and cut into chips by cleavage to complete the surface-emitting type semiconductor element.

With respect to the wavelength band in which the surface-emitting type semiconductor device according to the present embodiment oscillates, In _0.5 (Ga _1−x4 A
l _x4 ) More than 600 nm and 70 from the _0.5 P quantum well active layer.
Control to a range of 0 nm or less is possible.

The GaAs substrate 61 of the above-mentioned surface-emitting type semiconductor device
The side is fixed to a heat sink, and similarly to the semiconductor laser device according to the first embodiment, the laser is excited by the semiconductor laser element 24 and the like, and a resonator is constituted by the external mirror and the distributed reflection film 62, so that the red It is possible to obtain an output and laser oscillation of the fundamental transverse mode.

The semiconductor laser devices according to the above two embodiments can perform not only CW operation but also Q-switch operation by inserting a Q-switch element into a resonator.

Alternatively, the semiconductor laser device for excitation may be pulse-driven, and the semiconductor laser device having the above-described configuration may be pulse-driven. In particular, an InGaN-based semiconductor laser element for excitation has a higher COD value (maximum light output at the time of end face breakdown) than other semiconductor laser elements, and is therefore an optimal excitation light source for pulse driving.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a semiconductor laser device constituting a semiconductor laser device according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view showing a surface-emitting type semiconductor element constituting the semiconductor laser device according to the first embodiment of the present invention;

FIG. 3 is a diagram showing a configuration of the semiconductor laser device according to the first embodiment of the present invention;

FIG. 4 is a cross-sectional view showing a surface-emitting type semiconductor element constituting a semiconductor laser device according to a second embodiment of the present invention;

[Explanation of symbols]

11 GaN substrates _{12,17 Ga 1-z1 Al z1 N} / GaN superlattice cladding layer 13, 16 GaN layer _{14 In 1-z2 Ga z2 N} / In 1-z3 Ga z3 N multiple quantum well active layer 15 p-Ga _{1 -z4} Al _z4 N carrier blocking layer 18 p-GaN contact layer 31 or 61 GaAs substrate _{32,63,67 In 0.5 (Ga 1-x2} Al x2) 0.5 P cladding layer 33,35,64,66 In _0.5 (Ga _{1 -x2} Al _x2 ) _0.5 P light confinement layer 36 2-pair InGaAlP / InAlP distributed reflective film 37 12 pairs of SiO ₂ / ZrO ₂ distributed reflective film 43 heat sink 45 wavelength control element 46 concave mirror 62 30 pairs of In _0.5 (Ga _1-x1 Al _x1 ) _0.5 P / In
_0.5 Al _0.5 P distributed reflection film 65 In _0.5 (Ga _1-x3 Al _x3 ) _0.5 P / In _0.5 (G
a _1-x4 Al _x4 ) _0.5 P multiple quantum well active layer 68 ZrO ₂ film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F073 AA45 AA62 AA64 AA71 AA74 AA77 AB16 AB17 AB21 AB25 AB27 AB29 CA07 CA14 CA17 DA05 DA21 EA24 GA36

Claims (8)

[Claims] 1. An excitation light source comprising a semiconductor laser device using InGaN or GaN for an active layer, and InGaAs on a substrate which emits laser light when excited by the excitation light source.
A semiconductor laser device comprising: a surface emitting semiconductor element having an active layer made of 1P or InGaP. 2. An excitation light source comprising a semiconductor laser element using InGaN or GaN for an active layer, and an active layer composed of InGaAlP or InGaP on a substrate which emits laser light when excited by the excitation light source. A semiconductor laser device comprising: a semiconductor layer; and a surface-emitting type semiconductor element having mirrors on both end surfaces of the semiconductor layer in a stacking direction. 3. An excitation light source composed of a semiconductor laser element using GaNAs or InGaNAs for an active layer, and an indium laser on a substrate which is excited by the excitation light source and emits laser light.
A semiconductor laser device comprising: a surface emitting semiconductor element having an active layer made of GaAlP or InGaP. 4. An excitation light source comprising a semiconductor laser element using GaNAs or InGaNAs as an active layer, and an active layer composed of InGaAlP or InGaP, which is excited by the excitation light source and emits laser light, is formed on a substrate. A semiconductor laser device comprising: a semiconductor layer; and a surface-emitting type semiconductor element having mirrors on both end surfaces of the semiconductor layer in a stacking direction. 5. An excitation light source comprising a semiconductor laser device using InGaN or GaN for an active layer, and InGaAlP on a substrate excited by the excitation light source.
Or a surface-emitting type semiconductor device provided with an active layer made of InGaP, and disposed outside the surface-emitting type semiconductor device and formed on the substrate side or the side opposite to the substrate of the active layer of the surface-emitting type semiconductor device. A semiconductor laser device comprising a mirror and an external mirror forming a resonator, and outputting laser light from the external mirror. 6. An excitation light source composed of a semiconductor laser device using GaNAs or InGaNAs for an active layer, and an InGaAlP on a substrate excited by the excitation light source.
Or a surface-emitting type semiconductor device provided with an active layer made of InGaP, and disposed outside the surface-emitting type semiconductor device and formed on the substrate side or the side opposite to the substrate of the active layer of the surface-emitting type semiconductor device. A semiconductor laser device comprising a mirror and an external mirror forming a resonator, and outputting laser light from the external mirror. 7. The semiconductor laser device according to claim 1, wherein the semiconductor laser element has a stripe-shaped current injection window, and a width of the stripe serving as the current injection window is 5 μm or more.
7. The semiconductor laser device according to 4, 5, or 6. 8. The laser beam has a wavelength of not less than 600 nm and not less than 7 nm.
The semiconductor laser device according to any one of claims 1 to 7, wherein the thickness is not more than 00 nm.